Hydraulic control devices

ABSTRACT

A hydraulic control device connected to one of a series of shifting rams in a hydraulic system for shifting a conveyor in a mine working. The device is composed of a piston disposed in a cylinder and one or more displaceable stop members for limiting the movement of the piston and thereby regulating the quantity of pressure medium supplied to the ram. The position of the, or each, stop member can be altered with a cam or similar eccentric rotatable member connected to a manually operable control knob. An automatic change-over valve is preferably used to connect the working chambers on either side of the piston to either a pressure source or to the ram.

United States Patent 1191 Schwan t ]March 20, 1973 [54] HYDRAULIC CONTROL DEVICES 3,288,071 11/1966 3,190,185 6/1965 [75] Inventor. Wolfgang Schwandt, Altlunen, Ger- 2,980,024 4/1961 many 3,007,464 ll/l96l Assigneez Gewerkschaft se utte westfal a, 3,510,235 Bensmger 6t X 2 33 2 near Lumen Westfaha Primary ExaminerMartin P. Schwadron y Assistant Examiner-Allen M. Ostrager [22] Filed: Dec. 31, 1970 Attorney-Sughrue, Rothwell, Mion, Zinn & Macpeak [2!] Appl. No.: 103,081 [57] ABSTRACT A hydraulic control device connected to one of a se- [30] Forelgn Apphcauon Pnomy Data ries of shifting rams in a hydraulic system for shifting a Jan. 30, 1970 Germany ..P 20 04 056.6 Conveyor in a mine working- The device is Composed of a piston disposed in a cylinder and one or more dis- 52 us. Cl. ..91/41s, 92/13, 60/54.5 R Placeable Stop members for limiting the movement of [51] Int. Cl ..F15b 11/16 the piston and thereby regulating the quantity of pres 58 Field of Search ..92/13 13.4 13.5 13.6 13.8' Sure medium Supplied the The 6 605,4 5 or each, stop member can be altered with a cam or similar eccentric rotatable member connected to a [56] References Cited manually operable control knob. An automatic change-over valve is preferably used to connect the UNITED ST ATES PATENTS working chambers on either side of the piston to either a pressure source or to the ram. 2,576,747 ll/l95l Bryant ..92/l3.6 X 3,422,926 1/1969 Stanaway ..92/ 13.6 X 1 Claim, 3 Drawing Figures .PATENTED HARPO I975 SHEET 2 0F 2 HYDRAULIC CONTROL DEVICES BACKGROUND TO THE INVENTION The present invention relates to a hydraulic control device and to a hydraulic system for shifting a conveyor or the like used for guiding a mining machine used in underground mine workings.

course of the newly exposed coal face can be determined by the conveyor as it guides the associated winning machine. With the aid of the shifting rams the conveyor can be secured at a certain preselected distance from the coal face in such a way that the winning machine cannot alter this distance so that a certain fixed loading for the machine can be maintained.

In the shifting system of this type known hitherto it has been a problem to supply the correct amount of pressure medium to each shifting ram to cause the ram to extend by the desired amount.

It is a general object of this invention to provide a control device enabling an improved shifting system to be constructed.

SUMMARY OF THE INVENTION In one aspect, theinvention provides a hydraulic control device comprising a cylinder, a piston mounted for sliding within said cylinder, a movable stop member capable of engaging the piston to limit its movement, and means for moving the stop member into various positions to thereby alter the distance by which the piston can be displaced.

In another aspect, the invention provides a hydraulic system for shifting a conveyor, said system comprising a plurality of shifting rams the stroke of at least one of shifting rams being controlled by means of a device composed of a cylinder with a working chamber connectible to the associated ram, a piston mounted for sliding within said cylinder to displace a predetermined quantity of pressure medium to the shifting ram, and at least one movable stop member capable of engaging the piston to limit its movement and means for moving the stop member to control the movement of said piston.

Two, stop members can be provided each capable of engaging one working surface of said piston and each having separate moving means associated therewith. According to a preferred embodiment of the invention, each moving means is in the form of a rotatable member mounted for rotation about an eccentric axis and said member is shaped as an irregular polyhedron with the outer surfaces of which can abut against thestop member.

In every setting position of the rotatable member the stop member rests against one of the outer surfaces of the rotatable member. The depth by which the stop member enters the associated chamber of the cylinder to limit the movement of the piston therein is thus determined by the distance between the outer surface of the rotatable member engaging the stop member and the axis of rotation of said rotatable member.

In another embodiment of the invention, the means for moving the stop member can be a cam mounted externally of the cylinder. Means such as notches or clamping devices, known in themselves can be provided, to enable the cam to be secured in the particular positions.

In a further feature of the invention the moving means can be disposed in a sub-housing detachably secured to said cylinder. The cylinder preferably has parts which allow pressure medium to be conveyed to or from the working chambers facing the wording faces of the piston. The, or each, rotatable member is connected to a manually operable control knob.

In a shifting system according to the invention the cylinder can have parts communicating with its working chambers and connected to the associated shifting ram and to a source of pressure medium. A changeover valve is preferably interposed between the parts on the one hand and the ram and pressure medium source on the other hand, said change-over valve being operable to connect one or other of the parts to the source of the ram.

A control conduit is preferably connected to said change-over valve said conduit serving to convey pressure medium to said valve to cause the latter to perform its change-over function. According to a further feature of the invention a shut-off valve is connected between one of said parts and to said pressure medium source and serves to lock the shifting ram hydraulically.

The device made in accordance with the invention offers the advantage that the abutment surfaces of the piston and the adjusting and stop members can be so designed and arranged that they suffer little wear and that the device is easy and simple to adjust.

The invention will be understood more readily, and various other features of the invention may become more apparent from consideration of the following description.

BRIEF DESCRIPTION OF DRAWINGS DESCRIPTION OF PREFERRED EMBODIMENTS Referring initially to FIG. 3, the stroke of a piston 1 of a hydraulic shifting ram used for moving a conveyor 3 is to be controlled by adjusting the quantity of pressure medium supplied to the cylinder 2 of the shifting ram. This quantity is adjusted by means of a device 4a made in accordance with the invention. It is to be understood that a number of such rams are arranged along the conveyor 3. The device 4a depicted in FIG. 3 is composed of two similar sections disposed at the left and right hand sides of the drawing. In contrast the device 4 depicted in FIGS. 1 and 2 has only one such section.

Referring now to FIGS. 1 and 2, the device as illustrated has a cylinder 5 within which is mounted a piston 6. At one end of the cylinder 5 there is disposed a stop member 8 displaceable axially of the cylinder 5. The stop member 8 is located in a bore provided in a wall 10 of a sub-housing l1 detachably secured to the cylinder 5, by means of a clamping ring 12 and screws 13. The member 8 is slidably located within the bore by means of a sealing element 14. An adjusting rotatable member 7 shaped as an irregular polyhedron, is rotatable about an eccentric axis within the sub-housing 11. The member 8 has an enlarged end portion disposed facing the member 7 and remote from the chamber 9 of the cylinder 5. The end most face 15 of this enlarged portion is engageable with one of the outer surfaces A of the adjusting member 7. By rotating the adjusting member 7 the distance by which the stop member 8 can be displaced before engaging the outer surface A of the member 7 in question can be altered. The adjusting member 7 is connected to a manually operable control knob 16 disposed externally of the housing 11 and carrying visually identifiable markings corresponding to the setting of the member 7. By adjusting the distance by which member 8 extends into the chamber 9 with the aid of the adjusting member 7 the effective volume of the chamber 9 can be increased or reduced, with a corresponding adjustment of the quantity of pressure medium fed through the device 4. Ports 17, 18 (FIG. 2) communicate with the cylinder 5 and by connecting the device 4 to a shifting ram such as is depicted in FIG. 3 the displacement of the conveyor 3 can be controlled.

As mentioned before, the device 4a shown in FIG. 3 differs from the device 4 shown in FIGS. 1 and 2 in that the cylinder 5 has two working chambers 9 each with a stop member 8 and associated parts. Each section of the device 4a composed of the parts 8, 9, 7, 11 operates as described hereinbefore. As shown in FIG. 3, the ports 17 and 18 are connected to conduits l9 and respectively. By means of a change-over valve 21, the conduits 19 and 20 can be selectively connected to a first conduit 22 leading to a source of pressure medium, not shown in the drawing, or to a second conduit 23 leading to the cylinder 2 of the shifting ram. The piston 6 of the device 4a is therefore subjected on one working surface or the other to pressure medium supplied through the conduit 22. The working surface of the piston 6 not exposed to the pressure medium supplied through the conduit 22 is thus displaced to eject a certain quantity of pressure medium which corresponds to the effective volume of the associated chamber selected by the members 7, 8. The aforesaid quantity of pressure medium is driven through a second conduit 23 to the cylinder 2 of the shifting ram.

As the conveyor 3 is normally moved up into position after each passage of the mineral winning plough, the operation of the change-over valve 21 is preferably ef fected automatically by means of separate pressure medium conveyed to the valve 21 via a control conduit 24 and initiated by the passage of the plough. To enable the change-over valve 21 to operate in opposition to the working pressure of the apparatus, the pressure of the fluid in the control conduit 24 is preferably slightly greater than the pressure of the fluid in the conduit 22 or 23.

To prevent the so-called breathing movement of the conveyor 23 during the passage of the plough the shifting ram is preferably locked after each working stroke. This operation can be performed by a shut-off valve 26 which communicates with the pressure medium conduit 19 and which can be opened via a by-pass conduit leading to the conduit 22. The shut-off valve 26 prevents any displacement of the pressure medium, both in the shifting ram and in the device 4a, and thus enables the shifting ram to be hydraulically locked.

lclaim:

l. A hydraulic control system for shifting a conveyor in mine working, comprising in combination, a plurality of shifting rams operatively connected to said conveyor, a plurality of control devices for controlling the position of said conveyor, each hydraulic control device operatively connected to and adapted for controlling the stroke of one of said rams, each of said hydraulic control devices comprising,

a main cylindrical housing;

a free-floating piston mounted for slidable movement within said main cylindrical housing, said piston having two oppositely disposed working surfaces;

an end wall located at each end of said main cylindrical housing;

two working chambers formed in said main cylindrical housing, each working chamber being defined at one end by a respective one of said working faces of said piston and at the other end by the respective end wall;

a first and second port in said cylindrical housing, each of said ports communicating with one of said working chambers in said cylindrical housing to convey fluid pressure to and from the respective chamber;

a sub-housing detachably secured to each end of the cylindrical housing, said sub-housings providing the end walls at each end of the cylindrical housa bore formed in each end wall provided by the subhousings;

a stop member slidably disposed in each of said bores and being displaceable into the adjacent working chamber axially of the cylindrical housing, each of said stop members being engageable with one of the working faces of said piston to limit the movement of the piston in the direction of the stop member;

sealing means disposed between the stop member and the wall of said bore to hydraulically seal the sub-housing from the working chamber formed in said cylindrical housing;

a rotatable control means disposed in each of said sub-housings for effecting separate displacements of each of said stop members to various positions to control the volume of the working chamber associated therewith and, accordingly, the quantity of fluid pressure fed into and out of said chamber, said rotatable control means including a rotatable body having an eccentric surface formed thereon in the form of an irregular polyhedron with a plurality of surfaces capable of selectively engaging the corresponding stop member for varying the position of said piston relative to each end wall;

a source of hydraulic fluid pressure;

conduit means operatively connecting said source of fluid pressure with said hydraulic control device and each of said shifting rams;

a change-over valve for each of said shifting rams connected in said conduit means, each changeover valve being selectively operable to connect one of the working chambers of said hydraulic control device to said source of hydraulic fluid pressure and the other of said working chambers 

1. A hydraulic control system for shifting a conveyor in mine working, comprising in combination, a plurality of shifting rams operatively connected to said conveyor, a plurality of control devices for controlling the position of said conveyor, each hydraulic control device operatively connected to and adapted for controlling the stroke of one of said rams, each of said hydraulic control devices comprising, a main cylindrical housing; a free-floating piston mounted for slidable movement within said main cylindrical housing, said piSton having two oppositely disposed working surfaces; an end wall located at each end of said main cylindrical housing; two working chambers formed in said main cylindrical housing, each working chamber being defined at one end by a respective one of said working faces of said piston and at the other end by the respective end wall; a first and second port in said cylindrical housing, each of said ports communicating with one of said working chambers in said cylindrical housing to convey fluid pressure to and from the respective chamber; a sub-housing detachably secured to each end of the cylindrical housing, said sub-housings providing the end walls at each end of the cylindrical housing; a bore formed in each end wall provided by the sub-housings; a stop member slidably disposed in each of said bores and being displaceable into the adjacent working chamber axially of the cylindrical housing, each of said stop members being engageable with one of the working faces of said piston to limit the movement of the piston in the direction of the stop member; sealing means disposed between the stop member and the wall of said bore to hydraulically seal the sub-housing from the working chamber formed in said cylindrical housing; a rotatable control means disposed in each of said sub-housings for effecting separate displacements of each of said stop members to various positions to control the volume of the working chamber associated therewith and, accordingly, the quantity of fluid pressure fed into and out of said chamber, said rotatable control means including a rotatable body having an eccentric surface formed thereon in the form of an irregular polyhedron with a plurality of surfaces capable of selectively engaging the corresponding stop member for varying the position of said piston relative to each end wall; a source of hydraulic fluid pressure; conduit means operatively connecting said source of fluid pressure with said hydraulic control device and each of said shifting rams; a change-over valve for each of said shifting rams connected in said conduit means, each change-over valve being selectively operable to connect one of the working chambers of said hydraulic control device to said source of hydraulic fluid pressure and the other of said working chambers of said device to the corresponding shifting ram, and a plurality of shut-off valves, each shut-off valve being connected in said conduit means for each hydraulic control device, and means for selectively operating said shut-off valves to selectively isolate a selected control device from its associated shifting ram to hydraulically lock the selected shifting ram. 